Question 1

How does the kinetic energy of a proton change when its relativistic mass doubles?

Accepted Answer

A)  It doubles. 
B)  It more than doubles. 
C)  It less than doubles. 
D)  It must increase but it is not possible to say how much. 
A)  It doubles. 
B)  It more than doubles. 
C)  It less than doubles. 
D)  It must increase but it is not possible to say how much.

Question 2

A spaceship is observed from the Earth to be moving toward a star at a speed of 0.80 c.If the distance from the spaceship to the star is 1.6 ly as measured from earth,how far is the star as measured from the moving space ship?

Accepted Answer

A)  2.1 ly 
B)  1.9 ly 
C)  1.6 ly 
D)  1.2 ly 
E)  0.96 ly 
A)  2.1 ly 
B)  1.9 ly 
C)  1.6 ly 
D)  1.2 ly 
E)  0.96 ly

Question 3

The sun radiates at a power of 3.9 $\times$ 1026 W.How long does it take for the sun to lose an amount of mass equal to the mass of the Earth (6.0 $\times$ 1024 kg)? Choose the first answer that is correct.

Accepted Answer

A)  less than one year 
B)  less than 1000 years 
C)  less than 106 years 
D)  less than 108 years 
E)  more than 108 years 
A)  less than one year 
B)  less than 1000 years 
C)  less than 106 years 
D)  less than 108 years 
E)  more than 108 years

Question 4

A spaceship is observed by a stationary observer to be moving at 0.600 c.A laser beam is shown straight ahead from the front of the spaceship.How fast does the laser beam travel relative to the observer?

Accepted Answer

A)  1.60 c 
B)  1.36 c 
C)  1.00 c 
D)  0.640 c 
E)  0.360 c 
A)  1.60 c 
B)  1.36 c 
C)  1.00 c 
D)  0.640 c 
E)  0.360 c

Question 5

How fast is a particle moving if its kinetic energy is equal to its rest energy?

Accepted Answer

A)  0.00 
B)  0.57 c 
C)  0.75 c 
D)  0.87 c 
E)  0.50 c 
A)  0.00 
B)  0.57 c 
C)  0.75 c 
D)  0.87 c 
E)  0.50 c

Question 6

Two cars are traveling down the highway in the same direction.Car A is traveling at 30.0 m/s and car B is passing car A at a relative speed of 3.0 m/s.What is the speed of car B with respect to the highway?

Accepted Answer

A)  27.0 m/s 
B)  30.0 m/s 
C)  33.0 m/s 
D)  32.9 m/s 
E)  33.1 m/s 
A)  27.0 m/s 
B)  30.0 m/s 
C)  33.0 m/s 
D)  32.9 m/s 
E)  33.1 m/s

Question 7

What speed is required for a length to contract to 80% of its proper length?

Accepted Answer

A)  0.80 c 
B)  0.60 c 
C)  0.40 c 
D)  0.20 c 
E)  0.50 c 
A)  0.80 c 
B)  0.60 c 
C)  0.40 c 
D)  0.20 c 
E)  0.50 c

Question 8

Calculate the speed of a beam of neutrons produced in a nuclear reactor,having kinetic energies of 1.0 MeV.The rest mass of neutrons is 939 MeV/c2.

Accepted Answer

A)  799 m/s 
B)  640 km/s 
C)  320 km/s 
D)  24.5 km/s 
A)  799 m/s 
B)  640 km/s 
C)  320 km/s 
D)  24.5 km/s

Question 9

If the velocity of a non-relativistic object is doubled,its energy is quadrupled.This is strictly true only for very low velocities.At what velocity is it the case that a doubling of velocity results in a doubling of energy?

Accepted Answer

A)  0.45c 
B)  0.33c 
C)  0.11c 
D)  0.20c 
E)  0.50c 
A)  0.45c 
B)  0.33c 
C)  0.11c 
D)  0.20c 
E)  0.50c

Question 10

A star like the sun has a luminosity of 3.9 $\times$ 1026 W.How much mass must be turned into energy each second to produce this power?

Accepted Answer

A)  1.3 $\times$ 1018 kg 
B)  4.3 $\times$ 109 kg 
C)  5.7 $\times$ 105 kg 
D)  5.9 $\times$ 106 kg 
E)  1.5 $\times$ 1011 kg 
A)  1.3 $\times$ 1018 kg 
B)  4.3 $\times$ 109 kg 
C)  5.7 $\times$ 105 kg 
D)  5.9 $\times$ 106 kg 
E)  1.5 $\times$ 1011 kg

Question 11

If the momentum of an electron is 1.53 MeV/c,what is its kinetic energy?

Accepted Answer

A)  1.53 MeV 
B)  1.02 MeV 
C)  1.44 MeV 
D)  1.10 MeV 
E)  2.59 MeV 
A)  1.53 MeV 
B)  1.02 MeV 
C)  1.44 MeV 
D)  1.10 MeV 
E)  2.59 MeV

Question 12

In the lab,charged particles are directed toward one another,each at speed 0.500 c.What is the speed of the particles moving toward the left with respect to the particles moving to the right?

Accepted Answer

A)  0.500 c 
B)  0.00 
C)  1.00 c 
D)  0.800 c 
E)  1.25 c 
A)  0.500 c 
B)  0.00 
C)  1.00 c 
D)  0.800 c 
E)  1.25 c

Question 13

Two cars are traveling down the highway in the same direction.Car A is traveling at 30.0 m/s and car B is passing car A at a relative speed of 3.0 m/s.Using Galilean relativity to calculate the speed of car B relative to the highway results in an answer incorrect by how many m/s?

Accepted Answer

A)  3.3 $\times$ 10-2 
B)  3.3 $\times$ 10-5 
C)  3.3 $\times$ 10-8 
D)  3.3 $\times$ 10-11 
E)  3.3 $\times$ 10-14 
A)  3.3 $\times$ 10-2 
B)  3.3 $\times$ 10-5 
C)  3.3 $\times$ 10-8 
D)  3.3 $\times$ 10-11 
E)  3.3 $\times$ 10-14

Question 14

A rocket speeding by the Earth is known,when at rest,to be roughly cylindrical with a radius of 15 m and a length of 150 m.When speeding by,its volume is measured to be 4.24 $\times$ 104 m3.What is its speed?

Accepted Answer

A)  0.917c 
B)  0.774c 
C)  0.678c 
D)  Insufficient information is given. 
A)  0.917c 
B)  0.774c 
C)  0.678c 
D)  Insufficient information is given.

Question 15

The mean life of muons is 2.2 $\mu$s.How fast are they moving if their measured mean life is 1.1 $\mu$s?

Accepted Answer

A)  0.50 c 
B)  0.87 c 
C)  0.56 c 
D)  0.94 c 
E)  This cannot happen. 
A)  0.50 c 
B)  0.87 c 
C)  0.56 c 
D)  0.94 c 
E)  This cannot happen.

Question 16

What error is made calculating the momentum of a particle moving at 0.80 c using classical mechanics rather than relativistic mechanics?

Accepted Answer

A)  less than 1% 
B)  the classical value is 67% too high 
C)  the classical value is 67% too low 
D)  the classical value is 40% too high 
E)  the classical value is 40% too low 
A)  less than 1% 
B)  the classical value is 67% too high 
C)  the classical value is 67% too low 
D)  the classical value is 40% too high 
E)  the classical value is 40% too low

Question 17

What is the magnitude of the momentum of a proton moving at 0.95 c? (mp = 1.67 $\times$ 10-27 kg)

Accepted Answer

A)  5.0 $\times$ 10-18 kg·m/s 
B)  4.8 $\times$ 10-18 kg·m/s 
C)  1.5 $\times$ 10-18 kg·m/s 
D)  9.5 $\times$ 10-18 kg·m/s 
E)  4.4 $\times$ 10-18 kg·m/s 
A)  5.0 $\times$ 10-18 kg·m/s 
B)  4.8 $\times$ 10-18 kg·m/s 
C)  1.5 $\times$ 10-18 kg·m/s 
D)  9.5 $\times$ 10-18 kg·m/s 
E)  4.4 $\times$ 10-18 kg·m/s

Question 18

A spear is thrown by you at a very high speed.As it passes,you measure its length at 1/2 its normal length.From this you conclude that the moving spear's mass must be

Accepted Answer

A)  one-half its rest mass. 
B)  twice its rest mass. 
C)  four times its rest mass. 
D)  None of these choices are correct. 
A)  one-half its rest mass. 
B)  twice its rest mass. 
C)  four times its rest mass. 
D)  None of these choices are correct.

Question 19

A spaceship is 25 m wide and 100 m long.When traveling at 0.80 c (in a direction along its length),what is its observed width?

Accepted Answer

A)  42 m 
B)  25 m 
C)  16 m 
D)  15 m 
E)  20 m 
A)  42 m 
B)  25 m 
C)  16 m 
D)  15 m 
E)  20 m

Question 20

An astronaut in a rocket with a speed v-0.6c relative to Earth performs a collision experiment and concludes that both momentum and energy are conserved.What would an Earth observer conclude?

Accepted Answer

A)  Neither energy nor momentum is conserved. 
B)  The collision never happened because the two objects are never in the same place at the same time. 
C)  Energy is conserved,but momentum is not. 
D)  Momentum is conserved,but energy is not. 
E)  Both momentum and energy are conserved. 
A)  Neither energy nor momentum is conserved. 
B)  The collision never happened because the two objects are never in the same place at the same time. 
C)  Energy is conserved,but momentum is not. 
D)  Momentum is conserved,but energy is not. 
E)  Both momentum and energy are conserved.

Exam 26: Relativity

How does the kinetic energy of a proton change when its relativistic mass doubles?

A spaceship is observed from the Earth to be moving toward a star at a speed of 0.80 c.If the distance from the spaceship to the star is 1.6 ly as measured from earth,how far is the star as measured from the moving space ship?

The sun radiates at a power of 3.9 ×\times× 1026 W.How long does it take for the sun to lose an amount of mass equal to the mass of the Earth (6.0 ×\times× 1024 kg)? Choose the first answer that is correct.

A spaceship is observed by a stationary observer to be moving at 0.600 c.A laser beam is shown straight ahead from the front of the spaceship.How fast does the laser beam travel relative to the observer?

How fast is a particle moving if its kinetic energy is equal to its rest energy?

Two cars are traveling down the highway in the same direction.Car A is traveling at 30.0 m/s and car B is passing car A at a relative speed of 3.0 m/s.What is the speed of car B with respect to the highway?

What speed is required for a length to contract to 80% of its proper length?

Calculate the speed of a beam of neutrons produced in a nuclear reactor,having kinetic energies of 1.0 MeV.The rest mass of neutrons is 939 MeV/c2.

If the velocity of a non-relativistic object is doubled,its energy is quadrupled.This is strictly true only for very low velocities.At what velocity is it the case that a doubling of velocity results in a doubling of energy?

A star like the sun has a luminosity of 3.9 ×\times× 1026 W.How much mass must be turned into energy each second to produce this power?

If the momentum of an electron is 1.53 MeV/c,what is its kinetic energy?

In the lab,charged particles are directed toward one another,each at speed 0.500 c.What is the speed of the particles moving toward the left with respect to the particles moving to the right?

Two cars are traveling down the highway in the same direction.Car A is traveling at 30.0 m/s and car B is passing car A at a relative speed of 3.0 m/s.Using Galilean relativity to calculate the speed of car B relative to the highway results in an answer incorrect by how many m/s?

A rocket speeding by the Earth is known,when at rest,to be roughly cylindrical with a radius of 15 m and a length of 150 m.When speeding by,its volume is measured to be 4.24 ×\times× 104 m3.What is its speed?

The mean life of muons is 2.2 μ\muμ s.How fast are they moving if their measured mean life is 1.1 μ\muμ s?

What error is made calculating the momentum of a particle moving at 0.80 c using classical mechanics rather than relativistic mechanics?

What is the magnitude of the momentum of a proton moving at 0.95 c? (mp = 1.67 ×\times× 10-27 kg)

A spear is thrown by you at a very high speed.As it passes,you measure its length at 1/2 its normal length.From this you conclude that the moving spear's mass must be

A spaceship is 25 m wide and 100 m long.When traveling at 0.80 c (in a direction along its length),what is its observed width?

An astronaut in a rocket with a speed v-0.6c relative to Earth performs a collision experiment and concludes that both momentum and energy are conserved.What would an Earth observer conclude?

Introduction

Force

Acceleration and Newtons Second Law of Motion

Motion With Constant Acceleration

Circular Motion

Conservation of Energy

Linear Momentum

Torque and Angular Momentum

Fluids

Elasticity and Oscillations

Waves

Sound

Temperature and the Ideal Gas

Heat

Thermodynamics

Electric Forces and Fields

Electric Potential

Electric Current and Circuits

Magnetic Forces and Fields

Electromagnetic Induction

Alternating Current

Electromagnetic Waves

Reflection and Refraction of Light

Optical Instruments

Interference and Diffraction

Early Quantum Physics and the Photon

Quantum Physics

Nuclear Physics

Particle Physics

Filters

The sun radiates at a power of 3.9 $\times$ 10²⁶ W.How long does it take for the sun to lose an amount of mass equal to the mass of the Earth (6.0 $\times$ 10²⁴ kg)? Choose the first answer that is correct.

Calculate the speed of a beam of neutrons produced in a nuclear reactor,having kinetic energies of 1.0 MeV.The rest mass of neutrons is 939 MeV/c².

A star like the sun has a luminosity of 3.9 $\times$ 10²⁶ W.How much mass must be turned into energy each second to produce this power?

A rocket speeding by the Earth is known,when at rest,to be roughly cylindrical with a radius of 15 m and a length of 150 m.When speeding by,its volume is measured to be 4.24 $\times$ 10⁴ m³.What is its speed?

The mean life of muons is 2.2 $\mu$ s.How fast are they moving if their measured mean life is 1.1 $\mu$ s?

What is the magnitude of the momentum of a proton moving at 0.95 c? (m_p = 1.67 $\times$ 10^-27 kg)